From: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
To: Mike Frysinger <vapier.adi@gmail.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] tcg shift ops and magnitudes larger than register size
Date: Thu, 13 Jan 2011 09:56:35 +0100 [thread overview]
Message-ID: <20110113085635.GA7296@edde.se.axis.com> (raw)
In-Reply-To: <AANLkTimaSKzA7QzW1C9y2-LSZgoCaJPZ2tiXN6vdpHJp@mail.gmail.com>
On Wed, Jan 12, 2011 at 08:13:45PM -0500, Mike Frysinger wrote:
> are there any rules with the tcg sar/shl/shr ops and their magnitudes
> ? such as "magnitudes cannot be larger than the register size" ?
Yes, the result is undefined in those cases.
> i have a 32bit register with the value of 0x1230002 and when i attempt
> to do a sari with a value >=32, it gives me 0x918001 (a single shift
> right has been done). i would have expected the value to be 0 (as
> that is what my architecture does).
You need to handle it in the translator. CRIS has similar semantics
as your arch. See target-cris/translate.c:t_gen_lsl() for one way
of doing it. There might be better ways though.
Cheers
next prev parent reply other threads:[~2011-01-13 8:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-13 1:13 [Qemu-devel] tcg shift ops and magnitudes larger than register size Mike Frysinger
2011-01-13 8:56 ` Edgar E. Iglesias [this message]
2011-01-14 23:26 ` Stuart Brady
2011-01-15 21:00 ` Edgar E. Iglesias
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